PTO generator

[bucmeister]

Is tractor rpm linear to PTO rpm? In other words if it's 540 at 2600 rpm would it be 270 at 1800?

If pto rpm is truly linear to the engine speed and 2600 yields 540 then I believe would be 1300 that should give you 270. The real question, as a few others have alluded to is the hp output at the reduced engine speed. What I believe you need is the power curve data for your particular tractor to give you some specifics on what hp you are getting at given rpm points. It could be that lowering your engine rpm by a 1/3 you could lose almost 1/2 of your rated pto hp which will also be further reduced by your speed step up system. The torque loss alone from the step up is going to cost you output hp, additionally you also need to consider the slower lugging type response of the engine at the lower rpm to load changes, not a problem for lights and electric heaters but not good for refrigeration compressors.

At least this is a lot of what was pointed out to me when I was considering a similar project.

 

[alchemy]

If pto rpm is truly linear to the engine speed and 2600 yields 540 then I believe would be 1300 that should give you 270.

yeh I see I made a mistake. I was thinking 3600 I guess, but are they "truly" linear?

 

[boggen]

converting a gas gen to a PTO gen is above my head. with that said perhaps a different direction.

most of the cheaper generators out there are fairly loud. honda portable generators 5 or so years ago was the quietest gen out there. and going to assume still are. due to full side panels, top panel and under panel, and sound / vibration insulation within the panels. most other generators, just have the engine and muffler right there out in the open, allowing sound to go every were.

also doing a different muffler / larger muffler can help reduce noise.

the 3k watt honda i have, sets right out the front door of a cabin, and you can barely hear the gen out side, even with windows and door open.

if you are half way handy, you could build a box for generators to set in. even go as far as build the box on a pallet, and put generator inside. and have it as a lock box just for generator and easy to move with pallet forks.

you can buy sound proofing material, and just use a stapler, or some sort of silicon or adhesive and place all around on the inside of the box, to help reduce noise.

i do not have pictures on hand. but hopefully below diagram might help. of what i did, for a box to hold generator. to mainly keep mice, bugs, snow, ice, rain, sun from directly getting to generator. but it also helps quite the generator down more. when only 2 side end doors are open. i just have never needed to put in sound damping material / insulation due to how quiet things are already. but could easily, if need be.

 

[schmism]

and if belting.. figure slip too..

unless you run a toothed belt setup

 

[Dana Warner]

The bottom pulley on my generator has a diameter of 4.715. The top puller diameter is 15.75. To figure the correct pulley sizes I divided 540 by the desired speed of 1800 which equals 3.333. What ever bottom pulley that is used I needed the top pulley to be 3.333 times larger circumference. The above sizes were the best available diameters to get the correct speed off of my 540 pto. During our 7 day power outage I ran my tractor in high rpm pto to slow engine speed. The generator is a 7kw Onan. We ran 2 refrigerators, the oil furnace and a minimum of other electrical items. To make sure the output was correct a digital voltmeter was used to check house voltage often. I found that once the tractor rpm and voltage were correct it was very steady.

 

[Storm56]

Excellent work Dana!!

 

[ericher69]

Howdy,
It lugs down the engine pretty good.

Small tractor with 15KW pto generator which spins at 3600rpm. So you have the tractor noise and the generator noise.
Video Link: http://youtu.be/6gxUk7MRofY

Watched the video.

A few things

1.tractor in the video is a bx (no more than 20pto HP)

2. Running 12-13kW (OP wants to run 4kW)

3.OP has 31hp (26pto HP?)

4. Should have zero issues with engine lugging

 

[jenkinsph]

I have to agree with boggen on this, if you wan't quiet operation get a Honda 3000 inverter genset with a sound level of 58db. It will also be about as cheap to operate as anything you can get. That Belarus with the multitude of belts or chains isn't going to be as fuel efficient, won't be as responsive to changing loads and will make alot more noise. I atleast hope you would go by and listen to a Honda 3000 i inverter genset before you start this build.

I also have an Onan CMQD 5500 w genset which uses a Kubota diesel engine that is pretty quiet too but is around 70db+-. More noise than the Honda but still way less than the tractor and genny setup you are planning.

Now I like build your own projects but my experience and judgement would lead me to pass on this project.

 

[bucmeister]

yeh I see I made a mistake. I was thinking 3600 I guess, but are they "truly" linear?

Yeah, I have no idea if they are linear. Guess one would have to come up with a sensor of some type that would allow for the measuring the rpm of the pto shaft at a couple of different engine rpm levels..

 

[Todd727]

BTW, if the speed is wrong, the frequency will be wrong, which may lead to problems for some electronic devices.

Tractor-Driven Generators: Producing Quality Power